With regard to the background of the invention, it should be pointed out that the mechanical and electrical connection of the line embodied as a coil in an electrode catheter having a head or ring electrode—for example, in a cardiac pacemaker electrode—must be particularly reliable because an interruption in this connection would lead to failure of the electrode catheter, which could have fatal consequences for the patient. Furthermore, such a defect would necessitate replacement of the electrode catheter, which would in turn necessitate an interventional procedure with all the usual accompanying circumstances, risks and consequences for the patient.
Mechanical and electrical connections of the coil to the electrode based on welding and crimping processes are fundamentally known and customary through obvious prior use. Although such connections are quite acceptable with regard to their reliability, these known approaches still have various disadvantages.
In welding, the material of the coil must naturally be fundamentally weldable. To this extent, welding processes cannot be used with coil wires made of various core and sheath materials, which have different melting points. Furthermore, the materials to be joined must be coordinated with one another, so that they can be welded to one another. This depends on the melting points of the welding partners and the diffusion of alloy elements therein. This may lead to embrittlement of the joining partners in the area of the heat influence zone. Components having very thin walls within the electrode device are fundamentally very problematical to weld. Another disadvantage is the inability to inspect such a welded joint. It is quite possible for an initial inspection for mechanical strength and electrical contact to be positive even if the weld is defective in the long run. Finally, even the smallest impurities on the components may lead to incomplete welded joints and thus result in manufacturing rejects.
The crimping mentioned above has safety deficiencies from the standpoint of production technology inasmuch as the quality of the joint usually depends on the hardness of the components. Furthermore, small diameters of components involved in a crimped connection are not possible because it is necessary to provide certain minimum wall thicknesses and a design of the joint adapted to the crimping technique together with an essential supporting structure and a separate crimping sleeve.
Against the background of the problems associated with the state of the art described above, an object of the present invention is to improve upon an electrode connection in its fixation device for the electrode end of the coil to the electrode, so that a secure mechanical and electrical connection of the coil to the electrode can be created, regardless of the materials used.